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Example Questions
Example Question #1 : Equilibrium
Consider the following reaction:
Give the expression for the equilibrium constant for this reaction.
Recall how to find the expression of the equilibrium constant for the simplified equation:
Since the given equation has gases, we will only consider the partial pressures of each gas in the expression for the equilibrium constant. Remember that only molecules in aqueous and gas forms are included in this expression. Pure solids and pure liquids are excluded.
Thus, we can then write the following equilibrium constant for the given equation:
Example Question #1 : Chemical Equilibrium, Equilibrium Constant, And Reaction Quotient
Consider the following reaction:
The reaction mixture at initially contains
and
. At equilibrium,
. What is the equilibrium constant for the reaction?
Start by writing the equilibrium expression:
Now, create a chart like the following to keep track of the changes in concentration.
Initial | 0.750 | 2.00 | 0.00 |
Change | -0.100 | -0.025 | 0.200 |
Equilibrium | 0.650 | 19.75 | 0.200 |
Since we know that the concentration of HCl decreased by , we can use the stoichiometric ratios to deduce the amount of change for the oxygen gas and the chlorine gas.
Plug in the equilibrium concentrations into the expression for the equilibrium constant.
Example Question #1 : Chemical Equilibrium, Equilibrium Constant, And Reaction Quotient
Calculate the equilibrium constant at for the reaction by using free energies of formation.
Start by using the free energies of formation to find .
,
Recall the equation that links together with the equilibrium constant,
.
Plug in the given information and solve for .
Example Question #1 : Equilibrium
Consider a reaction mixture using the equation shown. At equilibrium the partial pressure of is
and the partial pressure of
is
. What is the partial pressure of
in this mixture if
at
?
or
or
or
or
or
Use algebra to solve for the partial pressure of .
Example Question #1 : Chemical Equilibrium, Equilibrium Constant, And Reaction Quotient
Considering the reaction shown, if the partial pressures of ,
, and
are
each, is the mixture at equilibrium? If not which direction will the reaction proceed to reach equilibrium if
?
No, the reaction will proceed left towards the reactants.
No, reaction will proceed right towards the products.
Yes
Yes, the reaction will move towards the products.
No, reaction will proceed right towards the products.
Since the reaction is not at equilibrium. This means that at equilibrium, the ratio of products to reactants is greater than at the given conditions. Thus, the reaction will move right towards the products to reach equilibrium.
Example Question #1 : Equilibrium
In the laboratory of
and
of
are reacted in a
beaker. At equilibrium
of
remain. Using the equation shown calculate the equilibrium constant.
Use an ice table and the equation to solve.
Initial
Change
Equilibrium
Example Question #1 : Equilibrium
Find the of the reaction if you start with
and end with
at
.
Use an ICE table and the equation to solve.
Initial
Change
Equilibrium
Example Question #1 : Chemical Equilibrium, Equilibrium Constant, And Reaction Quotient
Hypobromous acid will dissociate in water at with a
. What is the
for this dissociation process?
For this question, we're given the acid dissociation constant for a reaction that occurs at a given temperature. We're asked to find the standard free energy change for the reaction.
First, we're going to need to use an equation that relates standard free energy changes with an equilibrium constant, which is shown as follows.
With regards to the temperature, we will need to convert the units given in the question stem into units of Kelvin.
Knowing that is the ideal gas constant, we have all the information we need to solve for the value of
.
Example Question #131 : College Chemistry
Determine the acid dissociation constant expression for the given reaction.
Acid dissociation constant which is denoted as is the equilibrium constant for the ionization of an acid. Therefore, the numerator contains the product of the concentrations of the substances on the product side of the chemical equation. The denominator contains the product of the concentrations of the substances on the reactant side of the chemical equation.
is omitted in the acid dissociation constant expression because as the solvent it is in excess and therefore the change in its concentration is negligible in comparison to the other substances in solution.
Example Question #131 : College Chemistry
Consider the following equation at equilibrium:
What would happen if more were added to the system?
There would be no change in the system.
The reaction would shift towards the products.
There is not enough information to determine the effects of adding more into the system.
The reaction would shift towards the reactants.
The reaction would shift towards the reactants.
Recall Le Chatelier's principle: A chemical system at equilibrium will shift in the direction that minimizes the disturbance to the system.
Before the addition of , the system is in equilibrium, meaning the reaction quotient is equal to the equilibrium constant;
.
However, after the addition of , a product, the reaction quotient is now less than the equilibrium constant;
.
In order to maintain equilibrium, the reaction will then shift left to favor the reactants in this chemical system.
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